The invention relates to batteries having very high rate capabilities. More particularly, the invention relates to batteries having metal vanadium oxides that can produce extremely high current densities. These batteries are particularly useful for implantable medical devices, especially defibrillators.
Lithium-based batteries have become commercially successful due to their relatively high energy density. Suitable positive electrode materials for lithium-based batteries include materials that can intercalate lithium atoms into their lattice. The negative electrode can be lithium metal, lithium alloys or compounds that can reversibly intercalate lithium atoms into their lattice. In conventional terminology, lithium-based batteries formed from lithium metal or lithium alloy negative electrodes are-referred to as lithium batteries while batteries formed with an anode (negative electrode) active material that can intercalate lithium ions are referred to as lithium ion batteries.
In order to produce improved batteries, various materials have been examined for use as cathode (positive electrode):active materials for lithium based batteries. A variety of materials, generally chalcogenides, are useful in lithium based batteries. For example, vanadium oxides in certain oxidation states are effective materials for the commercial production of positive electrodes for lithium based batteries. Also, metal vanadium oxide compositions have been identified as having high energy densities and high power densities, when used in positive electrodes for lithium based batteries. Silver vanadium oxide has a particularly high energy density and high power densities, when used in lithium based batteries. Silver vanadium oxide batteries have found particular use in the production of implantable cardiac defibrillators where the battery must be able to recharge a capacitor to deliver large pulses of energy in rapid succession.
In a first aspect, the invention pertains to a battery comprising an electrolyte having lithium ions and a cathode comprising silver vanadium oxide particles. The battery has a pulsed specific energy of at least about 575 mwh/g when pulsed in groups of four-10 second pulses at a current density of 25 mA/cm2 spaced by 15 seconds between each pulse and with 3.0 minutes between pulse groups down to a pulse discharge voltage of 1.5 V. The battery can be used in a defibrillator, a pacemaker or a combination thereof.
In another aspect, the invention pertains to a battery comprising silver vanadium oxide particles. The battery has a maximum pulse specific power of greater than about 1.5 W/g to 1.5 V.
Moreover, the invention pertains to a method for producing silver vanadium oxide particles the method comprising heating a mixture of vanadium oxide powder and a silver compound in a vessel with agitation of the reactants.
In addition, the invention pertains to a method for producing an electrode, the method including mixing a battery composition with low shear in a homogenizer and forming the mixed composition into an electrode. The battery composition comprises silver vanadium oxide particles, electrically conductive particles, binder and solvent.
In another aspect, the invention pertains to a battery comprising an anode comprising lithium metal foil, a cathode comprising silver vanadium oxide particles and an electrolyte having a solvent comprising alkylene carbonate and at least about 25 percent by volume 1,2-dimethoxyethane.
In a further aspect, the invention pertains to a method of producing vanadium oxide particles, the method comprising reacting a reactant stream comprising a vanadium precursor and water, wherein there is insufficient O2 to form the vanadium oxide product.
Furthermore, the invention pertains to a battery comprising a cathode having silver vanadium oxide particles, a binder and at least about 10 weight percent electrically conductive, electrochemically inert particles. The cathode has a thickness of at least about 0.8 mm.
In other embodiments, the invention pertains to a battery comprising a cathode having silver vanadium oxide particles, a binder and at least about 10 weight percent electrically conductive, electro-chemically inert particles. The cathode has a silver vanadium oxide density from about 1.8 g/cc to about 2.8 g/cc.
Moreover, the invention pertains to a battery comprising an electrolyte having lithium ions and a cathode comprising silver vanadium oxide particles, the battery being able to produce pulse trains with current densities of at least about 50 mA/cm2.
In addition, the invention pertains to a battery comprising an electrolyte having lithium ions and a cathode comprising silver vanadium oxide particles, the battery exhibiting no voltage delay near 2.6 volts in pulse operation.